Project description:Gibberellin (GA) promotes plant growth by destabilizing DELLA proteins. DELLA proteins integrate multiple hormonal and environmental stress responses. We investigated the role of GA and DELLA proteins in plant defence. We used microarrays to detail the global programme of gene expression controlled by DELLA proteins and identified distinct classes of differentially regulated genes in response to pathogens, hormones or pathogen elicitors. Experiment Overall Design: Five weeks old short day grown Arabidopsis leaf discs were used to treat with flg22 and samples were collected after 1 hour and 2 hour time points. For Alternaria brassicicola, five weeks old plants were drop inoculated with 4x 5µl droplets of Alternaria brassicicola spores (5x105 spores/ml) and samples were collected 3 days post inoculation. Five weeks old plants were infiltrated with Pst DC3000 (2x105cfu/ml) bacteria and samples were collected after 12 hours post infiltration. For methyl jasmonate treatments, five weeks old plants were sprayed with 10µM Methyl Jasmonate solution, covered with plastic bags and samples were collected after one hour.
Project description:Transcription profiling by array of Arabidopsis DELLA mutants after treatment with flg22, methyl jasmonate, Alternaria brassicicola or Pseudomonas syringae pv. tomato DC3000
Project description:Detection of bacterial flagellin by the tomato receptors Flagellin sensing 2 (Fls2) and Fls3 triggers activation of pattern-triggered immunity (PTI). We identified a tomato Fls2/Fls3-interacting receptor-like cytoplasmic kinase, Fir1, that is involved in PTI triggered by flagellin perception. Fir1 localized to the plasma membrane and interacted with Fls2 and Fls3 in yeast and in planta. CRISPR/Cas9-generated tomato fir1 mutants were impaired in several immune responses induced by the flagellin-derived peptides flg22 and flgII-28, including resistance to Pseudomonas syringae pv. tomato (Pst) DC3000, production of reactive oxygen species, and enhanced PR1b gene expression, but not MAP kinase phosphorylation. Remarkably, fir1 mutants developed larger Pst DC3000 populations than wild-type plants, whereas no differences were observed in wild-type and fir1 mutants plants infected with the flagellin deficient Pst DC3000deltafliC. fir1 mutants failed to close stomata when infected with Pst DC3000 and Pseudomonas fluorescens, and were more susceptible to Pst DC3000 than wild-type plants when inoculated by dipping, but not by vacuum-infiltration, indicating involvement of Fir1 in pre-invasion immunity. RNA-seq analysis detected fewer differentially expressed genes in fir1 mutants and altered expression of jasmonic acid (JA)-related genes. In support of JA response deregulation in fir1 mutants, these plants were similarly susceptible to Pst DC3000 and to the coronatine deficient Pst DC3118 strain, and more resistant to the necrotrophic fungus Botrytis cinerea following PTI activation. These results indicate that tomato Fir1 is required for a subset of flagellin-triggered PTI responses and support a model in which Fir1 negatively regulates JA signaling during PTI activation.
Project description:Arabidopsis MPK11 is activated and plays a role in the flg22 sensing. Mitogen-activated protein kinases (MAPKs) mediate cellular signal transduction during stress responses, as well as diverse growth and developmental steps in eukaryotes. Pathogen infection or treatment with conserved pathogen-associated molecular patterns (PAMPs) such as the bacterial flagellin-derived flg22 peptide are known to activate three Arabidopsis thaliana MAPKs, MPK3, MPK4 and MPK6. Several stresses, including flg22 treatment, are known to increase MPK11 expression but activation of MPK11 has not been shown. Here, we show that MPK11 activity can indeed be increased through flg22 elicitation. Expression profiling using a small-scale microarray for defense-related genes revealed that cinnamyl alcohol dehyrogenase 5 (CAD5) requires MPK11 for full flg22-induced expression. An mpk11 mutant showed increased flg22-mediated growth inhibition but no altered susceptibility to Pseudomonas syringae, Botrytis cinerea or Alternaria brassicicola.
Project description:Arabidopsis MPK11 is activated and plays a role in the flg22 sensing. Mitogen-activated protein kinases (MAPKs) mediate cellular signal transduction during stress responses, as well as diverse growth and developmental steps in eukaryotes. Pathogen infection or treatment with conserved pathogen-associated molecular patterns (PAMPs) such as the bacterial flagellin-derived flg22 peptide are known to activate three Arabidopsis thaliana MAPKs, MPK3, MPK4 and MPK6. Several stresses, including flg22 treatment, are known to increase MPK11 expression but activation of MPK11 has not been shown. Here, we show that MPK11 activity can indeed be increased through flg22 elicitation. Expression profiling using a small-scale microarray for defense-related genes revealed that cinnamyl alcohol dehyrogenase 5 (CAD5) requires MPK11 for full flg22-induced expression. An mpk11 mutant showed increased flg22-mediated growth inhibition but no altered susceptibility to Pseudomonas syringae, Botrytis cinerea or Alternaria brassicicola. A 24 DNA microarray study using toral RNA from an Arabidopsis mutant (mpk11 SALK049352) as well as wild type treated with water or flg22.
Project description:Pseudomonas syringae pv. tomato DC3000 (Pst) is a virulent pathogen, which causes disease on tomato and Arabidopsis. The type III secretion system (TTSS) plays a key role in pathogenesis by translocating virulence effectors from the bacteria into the plant host cell, while the phytotoxin coronatine (COR) contributes to virulence and disease symptom development. Recent studies suggest that both the TTSS and and COR are involved in the suppression of host basal defenses. However, little is known about the interplay between the host gene expression associated with basal defenses and the virulence activities of the TTSS and COR during infection. The global effects of the TTSS and COR on host gene expression associated with other host cellular processes during bacterial infection are also not well characterized. In this study, we used the Affymetrix full genome chip to determine the Arabidopsis transcriptome associated with basal defense to Pst DC3000 hrp mutants and the human pathogenic bacterium Escherichia coli O157:H7. We then used Pst DC3000 virulence mutants to characterize Arabidopsis transcriptional responses to the action of hrp-regulated virulence factors (e.g., TTSS and COR) during bacterial infection. Additionally, we used bacterial fliC mutants to assess the role of the PAMP flagellin in induction of basal defense-associated transcriptional responses. In total, our global gene expression analysis identified more than 5000 Arabidopsis genes that are reproducibly regulated more than 2-fold in three independent biological replicates of at least one type of comparison. Regulation of these genes provides a molecular signature for Arabidopsis basal defense to plant and human pathogenic bacteria, and illustrates both common and distinct global virulence effects of the TTSS, COR, and possibly other hrp-regulated virulence factors during Pst DC3000 infection. Experimenter name = William Underwood; Experimenter phone = 517-353-9182; Experimenter fax = 517-353-9168; Experimenter address = Michigan State University; Experimenter address = 222 Plant Biology Building; Experimenter address = 178 Wilson R.d. Experimenter address = East Lansing, MI; Experimenter zip/postal_code = 48824; Experimenter country = USA Experiment Overall Design: 40 samples were used in this experiment
Project description:Pseudomonas syringae pv. tomato DC3000 (Pst) is a virulent pathogen, which causes disease on tomato and Arabidopsis. The type III secretion system (TTSS) plays a key role in pathogenesis by translocating virulence effectors from the bacteria into the plant host cell, while the phytotoxin coronatine (COR) contributes to virulence and disease symptom development. Recent studies suggest that both the TTSS and and COR are involved in the suppression of host basal defenses. However, little is known about the interplay between the host gene expression associated with basal defenses and the virulence activities of the TTSS and COR during infection. The global effects of the TTSS and COR on host gene expression associated with other host cellular processes during bacterial infection are also not well characterized. In this study, we used the Affymetrix full genome chip to determine the Arabidopsis transcriptome associated with basal defense to Pst DC3000 hrp mutants and the human pathogenic bacterium Escherichia coli O157:H7. We then used Pst DC3000 virulence mutants to characterize Arabidopsis transcriptional responses to the action of hrp-regulated virulence factors (e.g., TTSS and COR) during bacterial infection. Additionally, we used bacterial fliC mutants to assess the role of the PAMP flagellin in induction of basal defense-associated transcriptional responses. In total, our global gene expression analysis identified more than 5000 Arabidopsis genes that are reproducibly regulated more than 2-fold in three independent biological replicates of at least one type of comparison. Regulation of these genes provides a molecular signature for Arabidopsis basal defense to plant and human pathogenic bacteria, and illustrates both common and distinct global virulence effects of the TTSS, COR, and possibly other hrp-regulated virulence factors during Pst DC3000 infection. Experimenter name = William Underwood Experimenter phone = 517-353-9182 Experimenter fax = 517-353-9168 Experimenter address = Michigan State University Experimenter address = 222 Plant Biology Building Experimenter address = 178 Wilson R.d. Experimenter address = East Lansing, MI Experimenter zip/postal_code = 48824 Experimenter country = USA Keywords: pathogenicity_design
Project description:SmD3 is a core protein of small nuclear ribonucleoproteins essential for pre-mRNA splicing. To assess the role of Arabidopsis SmD3-b in response to biotic stress we investigated sensitivity of the smd3-b mutant to Pseudomonas syringae pv. tomato DC3000 infection and its pathogenesis effectors flg22, elf18 and coronatine. We show that the mutant exhibits enhanced susceptibility to Pst accompanied with marked changes in the expression of key pathogenesis markers. mRNA levels of major biotic stress response factors were also altered upon treatment with Pseudomonas effectors. Our genome-wide transcriptome analysis of smd3-b mutant infected with Pst confirmed that lack of SmD3 protein deregulates defense to Pst DC3000 infection on the transcriptional level, including defects in splicing and altered pattern of alternative splicing. In addition, callose deposition, which is another marker of plant immunity, was strongly induced by elf18 and flg22 in the mutant, whereas production of reactive oxygen species triggered by flg22 was reduced. Finally, detection of phosphorylated forms of MPK3, MPK6 and MPK4/11 revealed higher activation of all MAPKs in the smd3-b mutant. All our data indicate that SmD3 contributes to plant immune response possibly via regulation of mRNA splicing of the key pathogenesis factors.
Project description:This study evaluates the transcriptome of Arabidopsis thaliana seedlings chronically exposed to the hormone Methyl Jasmonate (MeJA) or to the bacterial elicitor flg22 (a 22-amino acid peptide from flagellin). Treatments were performed under high and low phosphate availability using wild-type Col-0 plants and the phr1 phl1 mutant.
Project description:Purpose: The experiment is to compare the NGS-derived seedling and leaf transcriptome profiling (RNAseq) of an Arabidopsis mutant ahl13 with that of wild type upon bacterial pathogen (pst DC3000) and flagellin elicitation. Method: The mRNA profiles of 10-day-old wild-type (WT) and AHL13 knockout (ahl13, SALK_014014) Arabidopsis were generated by RNAseq using Illumina NovaSeq6000. The sequence reads were passed through quality filters and mapped to Arabidopsis genome by TopHat2 followed by transcript splicing and quantitation by Cufflinks. DESeq was done to analyze differential gene expressions. qRT–PCR validation was performed using SYBR Green assays Result: We mapped about 20 million sequencing reads per sample to the Arabidopsis genome and identified approximately 28,000 transcripts in the Arabidopsis Col-0 and ahl13 mutant using TopHat2. Differentially expressed genes were identified using DESeq2 and about 166 genes show up-regulation in ahl13 upon DC3000 infection (FC>2, FDR<0.01) Conclusions: The ahl13 mutant exhibit differential transcription profile from that of Col-0 upon DC3000 treatment but similar upon flg22 treatment.